Japan and the Philippines will hold their first joint naval drill this month in the West Philippine Sea, aka. South China Sea near a disputed shoal claimed by Beijing, sources in Tokyo and the Philippines said.

The May 12 maritime safety exercise, which will practice the code for unplanned encounters at sea, known as CUES, is part of an agreement signed by Japan and the Philippines in January aimed at tightening security cooperation.

The presence of Japanese naval vessels in the South China Sea may set signals of Japan’s growing interest in the region, and may irritate Beijing as criticism of its land reclamation projects there mounts.

“The exercise will not be far from Scarborough Shoal,” one of the sources in Japan said, referring to a rocky outcrop which China seized in 2012 after a three-month standoff with the Philippines.

The two-hour practice within Philippines territorial waters near Subic Bay, a former US navy base, will involve a Japanese warship and a Philippines navy frigate, a spokesman at the Philippine Navy said.

Japan’s military is considering joining the United States in maritime air patrols in the South China Sea as a counterweight to growing Chinese power, sources familiar with the discussions told Reuters last month.

That strategy, which is being encouraged by the Philippines, is spurring closer security ties between Manila and Tokyo. Their defense agreement in January also established regular vice-ministerial defense talks and exchanges of senior officers.